Spting2.5後就可以使用Annotation的部分,在使用上面(較容易)可以取代原先XML的設定,但若是遇上Annotation和XML衝突的時候,則會以XML為主。
- Required (可使用在setter上)
Customer.java
package com.example ;
import org.springframework.beans.factory.annotation.Required;
public class Customer {
private String name ;
private int age ;
public String getName() {
return name;
}
@Required
public void setName(String name) {
this.name = name;
}
public int getAge() {
return age;
}
@Required
public void setAge(int age) {
this.age = age;
}
}
Main.java
package com.example ;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
public class Main {
public static void main(String[] args) {
ApplicationContext context =
new ClassPathXmlApplicationContext("Beans.xml");
Customer cust = (Customer) context.getBean("Customer");
System.out.println("name:"+cust.getName()) ;
System.out.println("age:"+cust.getAge()) ;
}
}
設定檔必需加入<context:annotation-config/>,在Annotation有Required設定的情況下,若設定檔無設定的情況會造成BeanInitializationException: Property 'age' is required for bean 'Customer'
Beans.xml
<context:annotation-config/>
<!-- Definition for Customer bean -->
<bean id="Customer" class="com.example.Customer" >
<property name="name" value="Paul"/>
<!-- <property name="age" value="31"/> -->
</bean>
- Autowired (可使用在setter、constructor和property上)
1.setter
Customer.java
package com.example1;
import org.springframework.beans.factory.annotation.Autowired;
public class Customer
{
private Address address;
public Address getAddress() {
return address;
}
@Autowired
public void setAddress(Address address) {
this.address = address;
}
@Override
public String toString() {
return "Customer [address=" + address + "]";
}
}
Address.java
package com.example1;
public class Address
{
private String fulladdress;
public String getFulladdress() {
return fulladdress;
}
public void setFulladdress(String fulladdress) {
this.fulladdress = fulladdress;
}
@Override
public String toString() {
return "Address [fulladdress=" + fulladdress + "]";
}
}
Main.java
package com.example1;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
public class Main {
public static void main(String[] args) {
ApplicationContext context = new ClassPathXmlApplicationContext(
"Beans1.xml");
Customer cust = (Customer) context.getBean("customer");
System.out.println(cust);
}
}
Beans1.xml
<context:annotation-config/>
<bean id="customer" class="com.example1.Customer" />
<bean id="address" class="com.example1.Address" >
<property name="fulladdress" value="Taipei, TW" />
</bean>
結果顯示如下所示:
Customer [address=Address [fulladdress=Taipei, TW]]
2.constructor
Developer.java
package com.example2;
import org.springframework.beans.factory.annotation.Autowired;
public class Developer {
private Language language;
@Autowired
public Developer(Language language) {
this.language = language;
}
@Override
public String toString() {
return "Developer [language=" + language + "]";
}
}
Language.java
package com.example2;
public class Language {
private String name;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
@Override
public String toString() {
return "Language [name=" + name + "]";
}
}
Main.java
package com.example2;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
public class Main {
public static void main(String[] args) {
ApplicationContext context = new ClassPathXmlApplicationContext(
"Beans2.xml");
Developer developer = (Developer) context.getBean("developer");
System.out.println(developer);
}
}
Beans2.xml
<context:annotation-config/>
<bean id="developer" class="com.example2.Developer"/>
<bean id="language" class="com.example2.Language" >
<property name="name" value="Java" />
</bean>
結果顯示如下所示:
Developer [language=Language [name=Java]]
3.property
Person.java
package com.example3;
import org.springframework.beans.factory.annotation.Autowired;
public class Person
{
@Autowired
private Ability ability;
public Ability getAbility() {
return ability;
}
public void setAbility(Ability ability) {
this.ability = ability;
}
@Override
public String toString() {
return "Person [ability=" + ability + "]";
}
}
Ability.java
package com.example3;
public class Ability
{
private String skill;
public String getSkill() {
return skill;
}
public void setSkill(String skill) {
this.skill = skill;
}
@Override
public String toString() {
return "Ability [skill=" + skill + "]";
}
}
Main.java
package com.example3;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
public class Main {
public static void main(String[] args) {
ApplicationContext context = new ClassPathXmlApplicationContext(
"Beans3.xml");
Person person = (Person) context.getBean("person");
System.out.println(person);
}
}
Beans3.xml
<context:annotation-config/>
<bean id="person" class="com.example3.Person" />
<bean id="invisible" class="com.example3.Ability" >
<property name="skill" value="Invisible" />
</bean>
結果顯示如下所示:
Person [ability=Ability [skill=Invisible]]
另外,@Autowired(required=false)的設定會使得抓到參數的值為default值。
Customer.java
package com.example ;
import org.springframework.beans.factory.annotation.Required;
import org.springframework.beans.factory.annotation.Autowired;
public class Customer {
private String name ;
private int age ;
public String getName() {
return name;
}
@Required
public void setName(String name) {
this.name = name;
}
public int getAge() {
return age;
}
@Autowired(required=false)
public void setAge(int age) {
this.age = age;
}
}
Main.java
package com.example ;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
public class Main {
public static void main(String[] args) {
ApplicationContext context =
new ClassPathXmlApplicationContext("Beans.xml");
Customer cust = (Customer) context.getBean("Customer");
System.out.println("name:"+cust.getName()) ;
System.out.println("age:"+cust.getAge()) ;
}
}
Beans.xml
<context:annotation-config/>
<!-- Definition for Customer bean -->
<bean id="Customer" class="com.example.Customer" >
<property name="name" value="Paul"/>
<!-- <property name="age" value="31"/> -->
</bean>
**結果顯示如下所示:
name:Paul
age:0
- Qualifier
使用上需和Autowired一起使用,主要是用來確認何種bean需要被注入。
Customer.java
package com.example4;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Qualifier;
public class Customer
{
@Autowired
@Qualifier("address1")
private Address address;
public Address getAddress() {
return address;
}
public void setAddress(Address address) {
this.address = address;
}
@Override
public String toString() {
return "Customer [address=" + address + "]";
}
}
Address.java
package com.example4;
public class Address
{
private String fulladdress;
public String getFulladdress() {
return fulladdress;
}
public void setFulladdress(String fulladdress) {
this.fulladdress = fulladdress;
}
@Override
public String toString() {
return "Address [fulladdress=" + fulladdress + "]";
}
}
Main.java
package com.example4;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
public class Main {
public static void main(String[] args) {
ApplicationContext context = new ClassPathXmlApplicationContext(
"Beans4.xml");
Customer cust = (Customer) context.getBean("customer");
System.out.println(cust);
}
}
Beans4.xml
<context:annotation-config/>
<bean id="customer" class="com.example4.Customer" />
<bean id="address1" class="com.example4.Address" >
<property name="fulladdress" value="Taipei, TW" />
</bean>
<bean id="address2" class="com.example4.Address" >
<property name="fulladdress" value="New York, American" />
</bean>
結果顯示如下所示:
Customer [address=Address [fulladdress=Taipei, TW]]
- PostConstruct and PreDestroy
可針對物件初始化和物件銷毀做annotation
HelloWorld.java
package com.example5 ;
import javax.annotation.*;
public class HelloWorld {
private String message ;
@PostConstruct
public void init(){
System.out.println("Initialization now") ;
}
public void getMessage(){
System.out.println("Your Message : " + message);
}
public void setMessage(String message) {
this.message = message;
}
@PreDestroy
public void destroy(){
System.out.println("Destory now") ;
}
}
Main.java
package com.example5 ;
import org.springframework.beans.factory.InitializingBean;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.AbstractApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
public class Main {
public static void main(String[] args) {
AbstractApplicationContext context =
new ClassPathXmlApplicationContext("Beans5.xml");
HelloWorld obj = (HelloWorld) context.getBean("helloWorld");
obj.getMessage();
context.registerShutdownHook();
}
}
Beans5.xml
<context:annotation-config/>
<bean id="helloWorld" class="com.example5.HelloWorld" init-method="init" destroy-method="destroy">
<property name="message" value="Hello World!"/>
</bean>
結果顯示如下所示:
Initialization now
Your Message : Hello World!
Destory now
- Configuration and Bean
利用Configuration and Bean Annotation可以不需使用設定檔。
HelloWorldConfig.java
package com.example6 ;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
@Configuration
public class HelloWorldConfig {
@Bean
public HelloWorld helloWorld(){
return new HelloWorld();
}
@Bean
public HelloWorld1 helloWorld1(){
return new HelloWorld1();
}
}
上述程式碼的設定等同於
<beans>
<bean id="helloWorld" class="com.example6.HelloWorld" />
</beans>
<beans>
<bean id="helloWorld1" class="com.example6.HelloWorld1" />
</beans>
HelloWorld.java
package com.example6 ;
public class HelloWorld {
private String message;
public void setMessage(String message){
this.message = message;
}
public String getMessage(){
return message ;
}
}
HelloWorld1.java
package com.example6 ;
public class HelloWorld1 {
private String message1;
public void setMessage(String message1){
this.message1 = message1;
}
public String getMessage(){
return message1 ;
}
}
Main.java
package com.example6 ;
import org.springframework.context.ApplicationContext;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;
public class Main {
public static void main(String[] args) {
ApplicationContext ctx = new AnnotationConfigApplicationContext(HelloWorldConfig.class);
HelloWorld obj = (HelloWorld) ctx.getBean(HelloWorld.class);
obj.setMessage("Hello world");
System.out.println(obj.getMessage()) ;
HelloWorld1 obj1 = (HelloWorld1) ctx.getBean(HelloWorld1.class);
obj1.setMessage("Hello world1");
System.out.println(obj1.getMessage()) ;
}
}
結果顯示如下所示:
Hello world
Hello world1
- import
@Configuration
public class ConfigA {
@Bean
public A a() {
return new A();
}
}
@Configuration
@Import(ConfigA.class)
public class ConfigB {
@Bean
public B a() {
return new A();
}
}
public static void main(String[] args) {
ApplicationContext ctx =
new AnnotationConfigApplicationContext(ConfigB.class);
A a = ctx.getBean(A.class);
B b = ctx.getBean(B.class);
}
- init-method and destroy-method
public class Foo {
public void init() {
// initialization logic
}
public void cleanup() {
// destruction logic
}
}
@Configuration
public class AppConfig {
@Bean(initMethod = "init", destroyMethod = "cleanup" )
public Foo foo() {
return new Foo();
}
}
- scope
@Configuration
public class AppConfig {
@Bean
@Scope("prototype")
public Foo foo() {
return new Foo();
}
}
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